Extensibility features include API aggregation (beta), CustomResourceDefinitions (beta) in favor of ThirdPartyResources, support for extensible admission controllers (alpha), pluggable cloud providers (alpha), and container runtime interface (CRI) enhancements.

## **Action Required Before Upgrading**

### Network

### Fixes

* ⬆ Upgrade Swagger UI copy of `oauth2-redirect.html` to include fixes for flavors of authorization code flows in Swagger UI. PR [#3439](https://github.com/tiangolo/fastapi/pull/3439) initial PR by [@koonpeng](https://github.com/koonpeng).

### HorizontalPodAutoscaler v2 graduates to GA

Version 2 of the HorizontalPodAutoscaler API graduates to stable in the 1.23 release. The HorizontalPodAutoscaler `autoscaling/v2beta2` API is deprecated in favor of the new `autoscaling/v2` API, which the Kubernetes project recommends for all use cases.

This release does *not* deprecate the v1 HorizontalPodAutoscaler API.

### Generic Ephemeral Volume feature graduates to GA

  - the node label `alpha.service-controller.kubernetes.io/exclude-balancer` which excludes a node from cloud load balancers (using Service Type=LoadBalancer) is deprecated in favor of `node.kubernetes.io/exclude-balancer`. Support for `alpha.service-controller.kubernetes.io/exclude-balancer` will be removed in v1.18.

- Features:

// eu : https://www.iana.org/domains/root/db/eu.html
eu

// fi : https://www.iana.org/domains/root/db/fi.html
fi
// aland.fi : https://www.iana.org/domains/root/db/ax.html
// This domain is being phased out in favor of .ax. As there are still many
// domains under aland.fi, we still keep it on the list until aland.fi is
// completely removed.
aland.fi

// fj : http://domains.fj/

    * Bump metadata agent version to 0.2-0.0.21-1.
    * Expand the metadata agent's access to all API groups.
    * Remove metadata agent config maps in favor of command line flags.
    * Update the metadata agent's liveness probe to a new /healthz handler.
    * Logging Agent Improvements
    * Bump logging agent version to 0.2-1.5.33-1-k8s-1.

Related to this topic, the in-tree Azure and GCP authentication plugins have been [deprecated](https://github.com/kubernetes/kubernetes/pull/102181) in favor of out-of-tree implementations.

### Server-side Apply graduates to GA